Automatically controlled radioreceiver



W. VAN B. ROBERTS AUTOMATICALLY CONTROLLED RADIORECEIVER Filed June 27, 1929 INVENTOR WALTER VAN. B. ROBERT$ BY 7%MM ATTORN EY Patented July 18, 1933 PATENT GFFICE WALTER VAN B. ROBERTS, PB-XNCETON, HEW JERSEY, ASSIGI IOE TO RADIO CORPORA- TION OF AMERICA,

A (7031903.,43'11936 O35 DELAWARE Application filed June 27,

My present invention relates to automatically controlled receivers, and, more particularly, to a novel means for automatically con- {trolling the tuning and volume of a radio receiver.

Automatically controlled radio recei 'z-z, especially of the push-botton type, are welt known. These prior devices, however, are unnecessarily complicated in th ir merhant cal structure. For example, they often involve delicate mechanical adjustments, easily subject to abuse during operation of the set. Again, the control of output volume in prior automatic devices is independent of the tum ing mechanism; or, if automatic voliunc control is employed, expensively roinbined with the tuning device. These disadvantages, coupledwith the fact that an inexpensive, automatic ccciver is much more desirable than a highly complex and costly inecnanisn'z, make it necessary to improve prior automatic radio receivers.

Now, I have designed a receiver which will incorporate the desirable features of prior devices, and at the same time, retain the advantages of econon'iy and simplicity of opera tion. Briefly, the novel automatic radio receiver, herein disclosed, emlyiodies means so arranged that whatever station is selec ed, a volume control adjustment is simultaneously selected, the latter control having been adjusted for a predetern'iinod volume upon installation of the receiver( Thus, the present invention has for its in i u object the provision of an automatically con-- trolled radio receiver having; predetermined volume control combined with predetermined tuning, both control. and tuning being effected by the utilization of a simple selective switching means.

Another in'iportant object of the present invention is to provide a radio receiving set embodying a plurality of circu a, each of said circuits being fixedly tuned to a predetermined station, a plurality of selective switches connected to said circuits, each of said switches being connected with a predetermined one of said circuits, said switches being so constructed that it merely necessary to simultaneously connect the terminals 1929. Serial No. 374,801.

of the wires of a given circuit to obtain the station to which the circuit is tuned.

Another object of the invention is to proride :1 push-button type of radio receiver embodying station selector switches so designed that when a given switch is not in use the tuned circuit terminal contacts arranged in the said switch are electro-statically shielded from each other, and novel key means for courier-ting the contacts to select a given station.

(it objects of the invention are to improve generally the simplicity and efficiency of automatically controlled radio receivers,

and to provide a push-button type of receiver which is durable, simple, reliable in operation, and economical to manufacture,

The novel features which I believe to be characteristic of my invention are set forth in, particularity in the appended claims, the invention itself, however, as to both it orgunizution and method of operation will best be understood. by reference to the following description taken in connection with the drawing; in which I have indicated diagrammatically one circuit organization whereby my invention may be carried into effect.

In the drawing,

1 shows diagrammatically a receiver circuit embodying the invention,

Fig. 2 is a detail view of a modified form of station selector.

Referring to the uccon'ipanying drawing, in which like characters of reference indicate the same parts in the di tl'erei'it views, there is shown in Fig". l, a grounded antenna circuit A, G, coupled, as at i l L, to the tuned input circuit of the first radio frequency tube 1. The tube 1 has been shown as a screerogrid type of electron emission device, it being understood, however, that the usual t-riode may be employed.

The filament of tube 1 is energized from a source A, the latter having its negative termin al grounded, there a fixed resistance a", and variable resistor V in series in the lead from the positive teri'ninal of the source to the positive leg of the filament. The negative leg of the filament is connected to a terminal contact P through a variable resistor R and terminals at each end for easy replacemei to a second terminal contact P through a resistor R At a point distant from contact P along the periphery of insulati on ring S, is disposed a grounded contact P A grounded contact P is similarly disposed in insulation ring S at a point distant from contact P In the input circuit of tube 1 are connected a plurality of fixed condensers. For simplieity of showing, only two such elements C and C: are shown. The fined .cndensor C is connected between the grid end of the coupling secondary and a contact l? disposed in ring S, the contact being spaced. from the corn tacts P an d P as shown. The fi ament end of the coupling secondary is grounded. it is to be noted that the fixed capacity C is removably connected to the input circi Ell? of tul ic 1, the points 4 denoting the means for maintaining the capacity in place.

The capacity may be of the well-known cartridge type, that is to say, m ranted within a protective cartridge casino; prcridizv' with a the circuit. The capacity C is so des l that it combines with the s condary of cou-- pling M] to provide a circuit tuned to a predetermined frequency.

A second. fixed capacity C also o the replaceable, cartridge type, is connected in the input circuit of tube 1 in a manner analogous to the connection of fixed capacity C one en d of the capacity being connected between the coupling secondary and grid of tube 1 and the other end to a contact P... This contact is disposed in the periphery of insulation ring S and is spaced, as shown, from contacts P, and P It is to be understood that the caacitv C2 is so desi ncd that it combines with a source having apotential. of )0 volts. there being an inductance L connected between the plate circuit and the positive terminal of the source, the capacity C, grounded. at. one terminal, being connected at its opposite end to the positive terminal ot the plate source.

The second stage of the tuned radio troquency includes the triode 2, which has its input circuit tuned by means of the inductance L, the replaceable, fixed capacity C and the replaceable fixed capacity C These latter capacities are preferably both of the cartridge type and are removably maintained in position by means denoted as 4, it being understood that these capacities may be interchanged with the capacities C C The capacity C3 is connected between the grid circuit of tube 2 and the contact P t the ring S and spaced from the remainin" contacts. The fixed capacity C is likewise connected between the grid circuit of he tube 2 and a contact P the latter being di: posed in the ring S and spaced from the othcr contacts in the said ring.

The tube 2 is rendered a:-:ymmctric in operation by the provision ot a capacity C; in the grid circuit thereof, and a grid 'sal: between its grid and filament. 'lhe liiamei t of tube 2 is energized from th source A, it being noted that this source also energizes the filament of tube 1, the negat ve ice of the filament of tube 2 being connected to contact P in. the rin S and contact 1 in the ring S Each 0t these crmtncts are spaced. from the contacts adjoiuin i; a. ill, :as shown clearly in Fig. 1. The positive F y; i the filament of tube 2 is connected to the positive terminal of source A tliroinrh a reactor 01,.

It is to he pointed out that the capacity Us,

is so designed that it combines with the inductance L to provide a circuit tuned to the ame frequency to which the circuit incl 'd- 111;; the capacity C,, is tuned. In the same manner the capacity C. combines with the in" d uc.ance L to provide a circuit tun-ed to the same trequencv to which the circuit xcluding the capaci y C is tuned.

The plate circuit of tube 2 is energized from a volt source, the said plate iicuit"" being coupled to the input circuit oi the first audio tube 3 through an audio Frequency coupling lVL. The grid of the audio tube 3 is biased by means of a source C, the posh tive terminal of the latter being connected between the negative oi the fibrin-exits of tubes 2 and 3.

It will be observed that the filament f tube 3 is connected in parallel with the filament of tube 2. and is energized from the same source A. The plate of" tube 3 is euergized from a volt source, the amplified output of the audio tube being uti ized n any well-known manner, as by plume-s, londspeaker, etc.

I haw. designated the ring S. for the purpose of illustration, as VIZ, and the ring 8, as VVEAF, it being understood that these designations represent the station call lrttcrs of the tuned circuits which a connected to each of the rings. These rings and their spective contacts will hereinatt be called station selector switcl'ics, it beine understood that it is merely necessary to insert a mctall ickey means in a ring in order to connect the various contacts disposed in a given ri." to an operative receiving circuit.' l; is ebvl one. of course. that each of the contacts are made of metal.

Thus, a metal key inserted in hole \VJZ connects all five terminals 17,. P P P and together. This connects condensers C, and C3 to the two ti'uied circuits, com oletes the filament circuits of the detector a nd audio tubes through the fixed resistance 11., and also,

closes the filament circuit of the screen grid tube 1 through fined resistance 1",, volume reducing resistance V and volume equalizing resistance R Placing a metal key or plug into aperture l VEAF does the same, except that condensers C and C, are connected in circuit so as to tune the receiver to VVEAF instead of ll'JZ, R being substituted for R it being understood that the key has been removed from the switch VVJZ. The resistor r so designed that it just permits rated current to flow in the filament when no other resistance is in the circuit. The resistor R is adjusted so that with the variable resistance V equal to Zero, the volume received from VVJZ is a desirable amount under the existing conditions (the particular antenna, location, time of day, etc).

Then, the resistance R is similarly adjusted to give a desired volume for lVEAF, preferably equal to that from U Should less volume be desired on either ion, variable resistance V is cut into circuit by means of a rheostat on the operating panel (not shown). It will be obvious that it will be necessary to have as many )ion selector switches as cartridge apacitics in the in ut circuits of tubes 1 and-2. 'lhesc cartridge capacities are very inexpensive, and it will therefore be uite economical to vary the number of stations desired to be selected from the broadcasting hand. If the metal hey or plug is removable it will be seen that the receiver is tamperqn'oof, inasmuch as only one possessing the key will be able to connect the contacts in a given switchv However, in Fig. 2, l have shown a type of selector switch in which a key 10 is permanently positioned in each of the selector switches, the particular insulation ring be ing designated, in Fig. 2 as S Six contacts are shown in this switch, assuming that three fixed capacities are used in the input circuit of the first radio stage. The contacts are elcctro-s'taticaily shielded from one another, when a particular selector switch not in use. It will be further observed that the lead wires to each cont ct may be protected by grounded shields shown in Fig g. 2, dotted lines. Each key it) is so designed that by moving it in the direction of the arrow all contacts are simultaneously connected to one another, while moving the key in the opposite direction simultaneously disconnects all contacts.

YVhile l have indicated and described one system for carrying my invention into effect, it will be apparent to one skilled in the art that my invention is by no means limited to the particular organization shown and described, but that many modifications in the circuit arrangements, as well as in the apparatus employed, may be made without departing from the scope of my invention as set forth in the appended claims.

What I claim is 1. In combination, in a radio receiver, a

plurality of radio frequency amplifier cir-T7 cuits, a frequency determining element in each circuit, an amplification control element, a source of energizing potential, a plurality of switches, each including a plurality of insulated contacts, one contact in each switchcu being grounded, the remaining contacts in each switch being connected to a predetermined frequency element, the amplification control element and potential. source, and a conductive key for electrically connecting all'iB the contacts in a given switch.

In combination, in a radio receiver, a plurality of radio frequency amplifier circuits, a frequency determining element in each circuit, an amplification control ole-C1 ment, a source of energizing potential, a plurality of switches, each including a plurality of insulated contacts, one contact in each switch being grounded, the remaining contacts in each predetermined frequency element, the amplification control element and potential source, a conductive key for electrically connecting all the contacts in a given switch, and means for elcctrostatically shielding each contact in 9 each switch.

3. A radio receiver comprising in combination. a adio frequency amplifier stage provided with a tuned input circuit, a detector stage, at least one tuned circuit disposed between the amplifie and the detector input, at least one stage of audio frequency amplification following the detector, a source of energizing current connected to the cathodes of the tubes of said stages, each of said tuncdi circuits including at least two frequency determining elements. at least two independent stat-ion selector switches each comprising a plu 'ality of spaced insulated contacts, elements in. said tun-ed circuits which resonate! connecting together the contacts of a desired switch.

l. A radio receiver comprising in combination, a radio frequency amplifier stage provided with a tuned input circuit, a detector stage, at least one tuned circuit disposed between the amplifier and the detector input, at least one stage of audio frequency amplification following the detector, a source of energizing current connected to the cathodes of the tubes of said stages, each of said switch being connected to ai the low potential end 11 tuned circuits including at least two frequency determining elements, at least two independent sta tion selector switches each comprising a plurality of spaced insulated con tacts, elements in said tuned circuits which resonate their circuits to the same frequency being connected to a. pair of contacts of the switch corresponding to said. same frequency, one contact of each switch being maintained at the same potential as the low potential end of said source, other contacts of each switch being connected to the high potential end of said source through said cathodes in each stage, conductive means for electrical 1y connecting together the contacts of a desired switch and an amplification control means connected between the cathode of said amplifier and a contact of each of said switches.

5. A radio receiver comprising in combi nation, a radio frequency amplifier stage provided with a tuned input circuit, a detector stage, at least one tuned circuit disposed tween the amplifier and the detector input, at least one stage'ot audio frequency amplification following the detector, :1 source of energizing current connected to the cathodes of the tubes of said stages, each of said tuned circuits including, at least two frequency determining elements, at least two independent station selector switches each comprising; a plurality of spaced insulated contacts, elements in said tuned circuit-s which resonate their circuits to the same frequency being connected to a pair of contacts of the switch corresponding to said samc'l'requency, one contact'of each switch being maintained at the same potential as the low potential end of said source, other contacts of each switch being connected to the high potential end of said. source through said cathodes in each stage, and conductive means consisting of a rotatable metallic key for electrically connecting together the contacts of a desired switcl'i.

6. A radio receiver comprising in combina tion, a radio frequency amplifier stage provided with a tuned input circuit, a detector stage, at least one tuned circuit disposed between the amplifier and the detector input,

at least one stage of audio frequency amplification following the detector, a source of energizing current connected to the cathodes of the tubes of said stages, each of said tuned circuits including at least two frequency determining elements, at least two independent station selector switches each comprising a plurality of spaced insulated contacts, elements in said tuned circuits which resonate their circuits to the same frequency being connected to a pair at contacts oi the switch corresponding to said same frequency, one contact of each switch being maintained at the same potential as the low potential end of said source, other contacts of each switch being connected to the high potential end of said source through said cathodes in each stagzje, and conductive means tor electrically connecting together the contacts t a desired switch, each of said elements (:m'npr sing a fixed condenser.

7. A radio receiver comprising in combi nation, a radio frequency amplifier stage provided with a tuned input circuit, a detector c, at least one tuned circuit disposed bei n the amplifier and the detector input, at itast one stage of audio frequency an'iplificae 'g'izing current connected to the cathodes of the tubes of said stages, each of said tuned circuits inc ui'linu at least two ircquency dctcrmining elements, at least two independent st 'on selector switches each comprising a plurality of spaced insulated contacts, elements in said tuned circuits which resonate their circuits to the same frequency being connected to a pair of contacts of the switch correiqaonding to said same frequency, one contact of each switch being maintained at the same potential the low potential end of said source, other contacts of each switch being; connected to the high potential end of said source through said cathodes in each stage, conductive means for electrically connecting together the contacts of a desired switch and means for electrostatically shielding' the contacts of each switch from one another.

VALTER VAN B. ROBERTS. 

